Centrifugal blower and method of assembling the same

ABSTRACT

A centrifugal blower assembly with reduced recirculation losses includes a housing defining an interior space and at least one inlet ring coupled to the housing to define an inlet into the interior space. The centrifugal blower assembly also includes an impeller configured to rotate about an axis to channel an airflow through the inlet and within the interior space. The impeller includes a plurality of blades that each include a notch formed therein, wherein the notch is radially aligned with the at least one inlet ring.

BACKGROUND

The field of the disclosure relates generally to centrifugal blowers,and more specifically, to centrifugal blowers that include an impellerthat improves blower efficiency and reduces blower noise.

Centrifugal blowers or fans are commonly used in the automotive, airhandling, and ventilation industries for directing large volumes offorced air, over a wide range of pressures, through a variety of airconditioning components. In some known centrifugal blowers, air is drawninto the blower housing through one or more inlet openings by animpeller, which defines an inlet chamber. At least some centrifugalblowers include a relatively large air gap between the inlet ring andthe end of the blades of the impeller. The larger the air gap betweenthe impeller blades and the inlet ring, the less efficient the operationof the impeller wheel. However, at least some air gap is desired toallow for manufacturing variations and impeller displacement when theblower system is subjected to external shock.

BRIEF DESCRIPTION

In one aspect, a centrifugal blower assembly is provided. Thecentrifugal blower assembly includes a housing defining an interiorspace and at least one inlet ring coupled to the housing to define aninlet into the interior space. The centrifugal blower assembly alsoincludes an impeller configured to rotate about an axis to channel anairflow through the inlet and within the interior space. The impellerincludes a plurality of blades that each include a notch formed therein,wherein the notch is radially aligned with the at least one inlet ring.

In yet another aspect, a method of assembling a centrifugal blowerassembly is provided. The method includes providing a housing thatdefines an interior space and positioning an impeller within the housingsuch that the impeller is configured to rotate about an axis to channelan airflow within the interior space. The impeller includes a pluralityof blades that each include a notch formed therein. The method alsoincludes coupling an inlet ring to the housing to define an inlet intothe interior space, wherein the inlet ring is radially aligned with eachnotch of the plurality of blades.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective of an exemplary centrifugal blower;

FIG. 2 is a cross-sectional view of the centrifugal blower shown in FIG.1;

FIG. 3 is a perspective view of an exemplary impeller wheel and inletrings for use with the centrifugal blower shown in FIG. 1;

FIG. 4 is a cross-sectional view of the impeller wheel and inlet ringsshown in FIG. 3;

FIG. 5 is an enlarged cross-sectional view illustrating an exemplarynotched blade of the impeller wheel;

FIG. 6 is an enlarged cross-sectional view illustrating an alternativeembodiment of a notched blade of the impeller wheel;

FIG. 7 is an enlarged cross-sectional view illustrating anotheralternative embodiment of a notched blade of the impeller wheel; and

FIG. 8 is an enlarged cross-sectional view illustrating yet anotheralternative embodiment of a notched blade of the impeller wheel.

Although specific features of various embodiments may be shown in somedrawings and not in others, this is for convenience only. Any feature ofany drawing may be referenced and/or claimed in combination with anyfeature of any other drawing.

DETAILED DESCRIPTION

The apparatus, methods, and systems described herein provide acentrifugal blower having increased efficiency due to a reduction inrecirculation losses. More specifically, the impeller described hereinincludes a plurality of blades that each include a notch formed at theconvergence of each blade's leading edge and axial end. The notch isradially aligned in the blower assembly with an inlet ring to reduce thedistance between the inlet ring and the blades, as compared to knownblower assemblies. In some embodiments, the inlet ring extends axiallybeyond an end ring of the impeller and into the notch on the blade suchthat the inlet ring axially overlaps with a portion of the blade.Including the notch on the blades reduces the distance between the axialend of the inlet ring and the blade to reduce recirculation losses andincrease efficiency. The notches create a “seal” between the impellerand the inlet ring to reduce the amount of air leaking between theimpeller and the inlet ring and bypassing the impeller. Additionally,the notches create clearance for manufacturing tolerances and forimpeller displacement should the blower assembly be subjected toexternal shock to prevent inlet ring-impeller striking. As such, thenotches enable a longer blade to reduce recirculation, while alsoallowing for potential impeller displacement.

FIG. 1 is a schematic perspective view of an exemplary centrifugalblower assembly 10. FIG. 2 is a cross-sectional view of centrifugalblower assembly 10. In the exemplary embodiment, centrifugal blowerassembly 10 includes a fan impeller 12 having an axis of rotation 14.Fan impeller 12 is coupled to a motor 16, which is configured to rotatefan impeller 12 about axis of rotation 14. In one embodiment, motor 16is an axial flux electric motor. In an alternative embodiment, motor 16is a radial flux electric motor. The rotation of fan impeller 12 drawsair into centrifugal blower assembly 10 along axis of rotation 14 asrepresented by airflow arrows 100, and expels the air radially outwardinto a housing 18. In the exemplary embodiment, fan impeller 12 isformed from a plurality of forward curved fan blades 20. Alternatively,fan blades 20 may include backward curved blades, airfoil blades,backward inclined blades, radial blades, or any other suitable bladeshape that enables fan impeller 12 to operate as described herein. Inthe exemplary embodiment, the shape of fan blades 20 of fan impeller 12facilitates reducing operating noise of fan impeller 12. Fan impeller 12is configured to produce a flow of air for a forced air system, e.g.,without limitation, a residential HVAC system.

In the exemplary embodiment, housing 18 includes a first sidewall 22 andan opposite second sidewall 24. Sidewalls 22 and 24 are fabricated asgenerally flat, parallel sidewalls disposed at axially opposite ends offan impeller 12. An outer periphery 26 of each of sidewalls 22 and 24 isshaped substantially the same and generally forms a volute shape withrespect to axis of rotation 14. In the exemplary embodiment, blowerassembly 10 further includes a scroll wall 28. More specifically, scrollwall 28 is coupled to outer periphery 26 of sidewalls 22 and 24 therebyforming an increasing expansion angle for airflow 100 through housing18. In the exemplary embodiment, scroll wall 28, which extends aroundfan impeller 12, includes a cutoff portion 30 including a cutoff point32 that is at least partially disposed within an interior space 34 ofhousing 18. Interior space 34 is defined at least by sidewalls 22 and 24and by scroll wall 28.

In the exemplary embodiment, housing 18 includes an air inlet opening 36provided in first sidewall 22 and another air inlet opening in secondsidewall 24. Specifically, in the exemplary embodiment, a respectiveinlet ring 42 is coupled to each of sidewalls 22 and 24 to define inletopenings 36 and includes an arcuate surface at inlet opening 36 toimprove blower assembly 10 efficiency. Further, an air outlet opening 38is defined, at least in part, by cutoff portion 30, sidewalls 22 and 24,and scroll wall 28. In the exemplary embodiment, airflow 100 is expelledfrom centrifugal blower assembly 10 through air outlet opening 38. Inthe exemplary embodiment, each component of housing 18 may be fabricatedfrom any material that enables housing 18 to function as describedherein, for example, without limitation, aluminum, steel,thermoplastics, fiber reinforced composite materials, or any combinationthereof.

Further, in the exemplary embodiment, motor 16 of centrifugal blowerassembly 10 is positioned in air inlet opening 36 and is coupled tohousing 18 by a motor mounting assembly 200 that includes an end shield(not shown) and a plurality of mounting arms 204. Alternatively, motor16 is coupled to blades 20 between sidewalls 22 and 24. Generally, motor16 is positioned in any location that enables operation of assembly 10as described herein.

In operation, fan impeller 12 rotates about axis of rotation 14 to drawair into housing 18 through air inlet opening 36. The amount of airmoved by centrifugal blower assembly 10 increases as fan impeller 12moves within housing 18 from cutoff point 32 towards air outlet opening38. Scroll wall 28 is positioned progressively further away from fanimpeller 12 in the direction of rotation of fan impeller 12 toaccommodate the increasing volume of air due to the volute shape ofhousing 18. Fan impeller 12 generates high velocity airflow 100 that isexhausted from air outlet opening 38. Fan impeller 12 draws airflow 100into centrifugal blower assembly 10 through air inlet opening 36 in theaxial direction (referring to axis of rotation 14) and turns airflow 100to a generally radial direction (generally perpendicular to axis ofrotation 14).

FIG. 3 is a perspective view of impeller 12 and inlet rings 42 withhousing 18 removed for clarity. FIG. 4 is a cross-sectional view ofimpeller 12 and one inlet ring 42. FIG. 5 is an enlarged cross-sectionalview illustrating an exemplary notched blade 20 of impeller 12. In theexemplary embodiment, each blade 12 includes a leading edge 40, atrailing edge 42, and a pair of opposing axial ends 44. As shown in FIG.5, the exemplary blade 20 also includes a twisted portion 46 extendingfrom axial end 44 and coupled to an end ring 48 of impeller 12. End ring48 is coupled to each blade 20 to support axial ends 44 in operation. Analternative blade type is illustrated in FIG. 6 that does not includetwisted portion 46 and the axial end is coupled directly to the endring, as described in further detail below.

In the exemplary embodiment, each blade 20 includes a notch 50 formedtherein. Specifically, notch 50 is defined at the convergence of leadingedge 40 and axial end 44 of blade 20. More specifically, notch 50 isdefined by a notch axial surface 52 extending from leading edge 40 andby a notch radial surface 54 extending from blade axial end 44. As shownin FIG. 5, axial surface 52 is oriented perpendicular to axis 14 andradial surface 54 is oriented parallel to axis 14. Although notch 50 isshown as rectangular with surfaces 52 and 54 illustrated as being planarand oriented perpendicular to each other, notch 50 includes any shapethat facilitates operation as described herein. For example, notch 50may also include curved surfaces, surfaces oriented obliquely withrespect to axis 14, or any combination thereof.

As best shown in FIG. 5, when blower assembly 10 is assembled andoperational, inlet ring 42 is radially aligned with and extends axiallyinto notch 50. That is, inlet ring 42 extends axially beyond end ring 48and beyond axial end 44 of blades 20 toward interior space 34. As such,inlet ring 42 partially overlaps notch radial surface 54 in the axialdirection. More specifically, inlet ring 42 includes a ring axial end 56and a ring radially outer surface 58. Ring axial end 56 is positionedinward, toward interior space 34, of both blade axial end 44 and endring 48.

Furthermore, ring axial end 56 and notch axial surface 52 define a firstgap 60 therebetween. In the exemplary embodiment, first gap 60 extends adistance D1 within the range of approximately 0.2 inches (in.) and 0.5in. More specifically, first gap 60 extends a distance D1 with the rangeof approximately 0.25 inches (in.) and 0.375 in. Generally, first gap 60extends any distance D1 that facilitates operation of blower assembly 10as described herein. Similarly, ring radially outer surface 58 and notchradial surface 54 define a second gap 62 therebetween. In the exemplaryembodiment, second gap 62 extends a distance D2 within the range ofapproximately 0.2 inches (in.) and 0.5 in. More specifically, second gap62 extends a distance D2 with the range of approximately 0.25 inches(in.) and 0.375 in. Generally, second gap 62 extends any distance D2that facilitates operation of blower assembly 10 as described herein. Inthe exemplary embodiment, gaps 60 and 62 are substantially equal insize. In another embodiment, gaps 60 and 62 are different in size.

Including notch 50 on blades 20 allows for a longer blade length, whichincreases the overall operation area of the blades 20. Increasing theoperational area increases the efficiency of the blades 20 because theclose proximity of the inlet ring 42 to blades 20 reduces recirculationlosses. Notch 50 creates a “seal” between impeller 12 and inlet ring 42to reduce the amount of air entering through inlet 36 from leakingbetween impeller 12 and inlet ring 42. Moreover, the small size of thegap between end ring 48 and inlet ring 42 further reduces recirculation,which also increases the efficiency of blower assembly 10. Additionally,notch 50 creates clearance for manufacturing tolerances and for impellerdisplacement when blower assembly 10 is subjected to external shock toprevent impeller 12 from impacting inlet ring 42. As such, notch 50enables a longer blade to reduce recirculation, while also allowing forpotential impeller displacement.

FIG. 6 is an enlarged cross-sectional view illustrating an alternativeembodiment of an impeller 112 for use in blower assembly 10. Impeller112 is substantially similar to impeller 12 (shown in FIG. 5) inoperation and composition, with the exception that blade 120 of impeller112 does not include the twisted portion 46 of blade 20 and end ring 148is a substantially flat disc rather than the roll crimped end ring 48 ofimpeller 12. As such, like components shown in FIG. 6, such as notch 50and inlet ring 42, are labeled with the same reference numbers used inFIG. 5. Impeller 112 may be substituted for impeller 12 for use withinblower assembly 10. Notch 50 on blade 120 provides the same advantagesas describe above with respect to blade 20. Furthermore, blade 120 maybe more efficient than blade 20 due to the increased operational lengthof blade 120 as a result of not having twisted portion 46, as blade 20does.

FIG. 7 is an enlarged cross-sectional view illustrating anotheralternative configuration of impeller 12 and inlet ring 42. In theconfiguration shown in FIG. 7, axial end 56 of inlet ring 42 is stillradially aligned with notch 50 of blade 20. However, axial end 56 ofinlet ring 42 is axially spaced a distance from axial end 44 of blade 20such that inlet ring 42 does not axially overlap with any portion ofblade 20. Furthermore, axial end 56 of inlet ring 42 is also axiallyspaced a distance from an axial end surface 49 of end ring 48 to definea minimal axial gap 64 between inlet ring 42 and end ring 48 to allowfor easier assembly. In such a configuration, even though inlet ring 42does not overlap with blade 20, notch 50 allows for end ring 48, andtherefore blades 20, to be positioned axially closer to inlet ring 42 toreduce recirculation and increase efficiency while preventing impeller12 from impacting inlet ring 42, as described herein.

FIG. 8 is an enlarged cross-sectional view illustrating yet anotheralternative configuration of impeller 112 and inlet ring 42. Theconfiguration of FIG. 8 illustrates a similar configuration as shown inFIG. 7 using impeller 112 rather than impeller 12. Specifically, axialend 56 of inlet ring 42 is still radially aligned with notch 50 of blade120. However, axial end 56 of inlet ring 42 is axially spaced a distancefrom axial end 144 of blade 120 such that inlet ring 42 does not axiallyoverlap with any portion of blade 120. Furthermore, axial end 56 ofinlet ring 42 is also minimally axially spaced a distance from an axialend surface 149 of end ring 148 to define a small axial gap 164 betweeninlet ring 42 and end ring 148. In such a configuration, even thoughinlet ring 42 does not overlap with blade 120, notch 50 allows for endring 148, and therefore blades 120, to be positioned axially closer toinlet ring 42 to reduce recirculation and increase efficiency, whilepreventing impeller 12 from impacting inlet ring 42, as describedherein.

The apparatus, methods, and systems described herein provide acentrifugal blower having increased efficiency. More specifically, theimpeller described herein includes a plurality of blades that eachinclude a notch formed at the convergence of the blades leading edge andthe blades axial end. The notch is radially aligned in the blowerassembly with an inlet ring to reduce the distance between the inletring and the blades, as compared to known blower assemblies. In someembodiments, the inlet ring extends axially beyond an end ring of theimpeller and into the notch on the blade such that the inlet ringaxially overlaps with a portion of the blade. Including the notch on theblades reduces the distance between the axial end of the inlet ring andthe blade to reduce recirculation losses and increase efficiency. Thenotches create a “seal” between the impeller and the inlet ring toreduce the amount of air from leaking between the impeller and the inletring and bypassing the impeller. Additionally, notches create clearancefor manufacturing tolerances and for impeller displacement should theblower assembly be subjected to external shock to prevent the impellerfrom impacting the inlet ring. As such, the notches enable a longerblade to reduce recirculation, while also allowing for potentialimpeller displacement.

Exemplary embodiments of the centrifugal blower are described above indetail. The centrifugal blower and its components are not limited to thespecific embodiments described herein, but rather, components of thesystems may be utilized independently and separately from othercomponents described herein. For example, the components may also beused in combination with other machine systems, methods, andapparatuses, and are not limited to practice with only the systems andapparatus as described herein. Rather, the exemplary embodiments can beimplemented and utilized in connection with many other applications.

Although specific features of various embodiments of the disclosure maybe shown in some drawings and not in others, this is for convenienceonly. In accordance with the principles of the disclosure, any featureof a drawing may be referenced and/or claimed in combination with anyfeature of any other drawing.

This written description uses examples to disclose the invention,including the best mode, and to enable any person skilled in the art topractice the invention, including making and using any devices orsystems and performing any incorporated methods. The patentable scope ofthe invention is defined by the claims, and may include other examplesthat occur to those skilled in the art. Such other examples are intendedto be within the scope of the claims if they have structural elementsthat do not differ from the literal language of the claims, or if theyinclude equivalent structural elements with insubstantial differencesfrom the literal languages of the claims.

What is claimed is:
 1. A centrifugal blower assembly comprising: ahousing defining an interior space; at least one inlet ring coupled tosaid housing and configured to define an inlet into the interior space;and an impeller configured to rotate about an axis to channel an airflowthrough the inlet and within the interior space, wherein said impellercomprises a plurality of blades that each include a notch formedtherein, wherein said notch is radially aligned with said at least oneinlet ring.
 2. The centrifugal blower assembly in accordance with claim1, wherein said at least one inlet ring extends into said notch.
 3. Thecentrifugal blower assembly in accordance with claim 1, wherein eachblade of said plurality of blades comprises a leading edge and a bladeaxial end, said notch defined at a convergence of said leading edge andsaid blade axial end.
 4. The centrifugal blower assembly in accordancewith claim 1, wherein each blade of said plurality of blades comprises aleading edge and a blade axial end, said notch defined by a notch axialsurface extending from said leading edge and a notch radial surfaceextending from said blade axial end.
 5. The centrifugal blower assemblyin accordance with claim 4, wherein said at least one inlet ring extendsaxially beyond said blade axial end.
 6. The centrifugal blower assemblyin accordance with claim 4, wherein said at least one inlet ring axiallyoverlaps said notch radial surface.
 7. The centrifugal blower assemblyin accordance with claim 4, wherein said at least one inlet ringcomprises a ring axial end, where a first gap is defined between saidring axial end and said notch axial surface.
 8. The centrifugal blowerassembly in accordance with claim 7, wherein said first gap is within arange of approximately 0.25 inches (in.) and 0.375 in.
 9. Thecentrifugal blower assembly in accordance with claim 7, wherein said atleast one inlet ring comprises a ring radially outer surface, where asecond gap is defined between said ring radially outer surface and saidnotch radial surface.
 10. The centrifugal blower assembly in accordancewith claim 9, wherein said second gap is within a range of approximately0.25 inches (in.) and 0.375 in.
 11. The centrifugal blower assembly inaccordance with claim 7, wherein said ring axial end is axially spacedfrom said blade axial end.
 12. The centrifugal blower assembly inaccordance with claim 1, wherein said impeller comprises an end ringcoupled to said plurality of blades.
 13. The centrifugal blower assemblyin accordance with claim 12, wherein said inlet ring extends axiallybeyond said end ring.
 14. The centrifugal blower assembly in accordancewith claim 12, wherein said inlet ring is axially spaced from said endring to define a gap therebetween.
 15. A method of assembling acentrifugal blower assembly, said method comprising: providing a housingthat defines an interior space; positioning an impeller within thehousing such that the impeller is configured to rotate about an axis tochannel an airflow within the interior space, wherein the impellerincludes a plurality of blades that each include a notch formed therein;and coupling an inlet ring to the housing to define an inlet into theinterior space, wherein the inlet ring is radially aligned with eachnotch of the plurality of blades.
 16. The method in accordance withclaim 15, wherein coupling the inlet ring comprises coupling the inletsuch that the inlet ring extends into each notch.
 17. The method inaccordance with claim 15, wherein coupling the inlet ring comprisescoupling the inlet such that the inlet ring extends axially beyond anaxial end of each blade and such that the inlet ring axially overlaps aradial surface of the notches.
 18. The method in accordance with claim15, wherein coupling the inlet ring comprises: coupling the inlet ringto define a first gap between an axial end of the inlet ring and anaxial surface of the notches; and coupling the inlet ring to define asecond gap between a radially outer surface of the inlet ring and aradial surface of the notches.
 19. The method in accordance with claim15, wherein coupling the inlet ring comprises coupling the inlet ringsuch that the inlet ring extends axially beyond an end ring of theimpeller.
 20. The method in accordance with claim 15, wherein couplingthe inlet ring comprises coupling the inlet ring to define an axial gapbetween the inlet ring and an end ring of the impeller.